1. Field of the Invention
The invention relates to acoustic echo cancellation, and more particularly to acoustic echo cancellation in full-duplex communication devices.
2. Description of the Related Art
A full-duplex communication device simultaneously transmits two-way signals to enable a near-end talker and a far-end talker to talk to each other. A full-duplex communication device has two channels, a line-in channel and a line-out channel. The line-in channel receives a far-end signal carrying voices of the far-end talker and broadcasts the far-end signal with a loudspeaker. The line-out channel converts voices of the near-end talker to a near-end signal with a microphone and transmits the near-end signal to the far-end talker. Thus, the near-end talker and the far-end talker separated by a distance can communicate with each other as if they are face to face.
Acoustic Echo cancellation is a major functional element for a hands-free full-duplex communication device. For a full-duplex communication device, a far-end signal carrying voices of a far-end talker should not interfere with a near-end signal carrying voices of a near-end talker. A microphone of a hands-free full-duplex communication device, however, is often located near a loudspeaker of the hands-free full-duplex communication device. When the loudspeaker broadcasts the far-end signal, the microphone converts a portion of voices of the far-end talker to the near-end signal with the voices of the near-end talker. Thus, echo occurs and should be eliminated from the near-end signal. Otherwise, when a far-end device receives and broadcasts the near-end signal, the far-end talker hears both voices of the near-end talker and of himself. Thus, a method for acoustic echo cancellation in a full-duplex communication device is required.